In a wireless local area network operated under the 802.11a/g/n/ac/ah/ax standards, an orthogonal frequency-division multiplexing (OFDM) scheme is used for digital multi-carrier modulation of signals. The first part of the preamble of each packet transmitted under this OFDM scheme includes a repeated sequence, the short training field (STF). The periodic property of STF can be used in the physical layer carrier sensing (CS) to detect whether a real data packet, instead of channel noise, is received and whether the CS is to be triggered. The packet decoding will only be performed after the carrier sensing is triggered. Therefore, when the channel condition is undesirable with a low signal-to-noise ratio (SNR), it can be difficult to distinguish real data contents from the noise, and, thus, carrier sensing performance may be negatively affected, which may reduce sensitivity of the entire receiver.